Although Bogomils regarded themselves as "Trinitarian", anathemas against Bogomils (circa 1027) charge Bogomils with rejection of the Trinity. Its followers refused to pay taxes, to work in serfdom, or to fight in conquering wars. They ignored the feudal social system, which was interpreted by their enemies as suggesting disorder if not the destruction of the state and church.
I've been reminded of Tisi's mention of Trinitarian by a curiosity in his own neighbourhood. A friendly Templar historian visiting us has mentioned the Strange Case of Claro Wapentakehttps://en.wikipedia.org/wiki/Claro_Wapentake
It's not a person, it's an old name for Knaresboroughhttps://en.wikipedia.org/wiki/Knaresborough
Robert of Knaresborough, son of the mayor of York, was the hermit living in a cave. But (it says) with servants.https://en.wikipedia.org/wiki/Robert_of_Knaresborough
Before his death St Robert established an order of Trinitarian Friars at Knaresborough Priory, but he warned them that when his time came the monks of Fountains abbey would try to carry his body away to their own establishment, he urged his followers to resist them, which they did and so St Robert was buried in his chapel cut from the steep rocky crags by the river, where it was said that a medicinal oil flowed from his tomb and pilgrims came from near and far to be healed by this.
This is the funny bit. My friend says she's never heard of Trinitarian Friars in Britain apart from this case. I'd never heard of them at all. But Trinitarian Friars were supposed to have been busy elsewhere:
The founding-intention for the Order was the ransom of Christians held captive by non-Christians, a consequence of crusading and of pirating along the Mediterranean coast of Europe
The Order was founded by John of Matha.
St. John founded the Trinitarians to go to the slave markets, buy the Christian slaves and set them free. To carry out this plan, the Trinitarians needed large amounts of money.
Why Knaresborough? Was it a centre for slave trading in Yorkshire? Or were there slave markets nearby?
I'm not so bothered about the monks of Fountains Abbey. That was founded because of a riot of its monks elsewhere. So clearly known in their own time as a rough lot. No wonder if St Robert suspected them of being body robbers, or likely to grab his valuable saintly relics while his body was still warm.